The basic principle of heat exchangers is that heat energy is transferred from a first media stream to a second media stream. The two media streams are not in fluid communication so that mixing does not take place.
In many embodiments, a housing is provided, through which a first medium flows. One or more conduits are arranged in the housing, in which a second medium flows. The media are separated from one another by the wall of the conduit. However, the wall allows heat transfer.
Heat exchangers are divided in terms of the direction of flow of the media streams into direct flow, countercurrent flow, and cross-flow heat exchangers. Direct flow means that the media flow substantially parallel to each other in the same direction. In counterflow, the media run substantially parallel but in the opposite direction. The term cross-flow is used when the media streams flow crosswise, in particular at an angle of 90°.
From the prior art, reactors are also known which comprise a heat exchanger. By a reactor is meant a container in which, when used as intended, a reaction takes place, especially a chemical or biochemical reaction.
Reactors may be used for example in the production of methanol (CH3OH). There, a reactor is fed carbon monoxide (CO) and hydrogen (H2), which react with each other in the reactor. In this case, a catalyst is used, which increases the reaction rate. The reaction is exothermic, so a removal of thermal energy is required.
From EP 1048343 A2 there is known a heat exchanger/reactor which can be used for the production of methanol and which comprises a plurality of straight conduits, in which a catalyst is arranged. The conduits are arranged in a housing through which flows a first medium, thereby bathing the conduits, and they emerge at the end side into a collection space and a distribution space situated opposite relative to the housing. Through the conduits flows a second medium, which consists of the raw materials and end products of the chemical reaction. The reaction takes place in the conduits. Owing to the exothermic reaction, a temperature gradient is produced from the conduits to the housing wall. Therefore, the conduits expand more strenuously than the housing wall, so that they by a respective bellows to the housing wall. The second medium transfers thermal energy to the first medium, which is transported with the first medium out from the housing.
The use of bellows is technically costly in processing and increases the costs of the device. In addition bellows are susceptible to wear, which is also disadvantageous.
WO 2013/004254 A1 proposes arranging the conduits movably in the longitudinal direction on the housing, without providing a bellows. In this way, the use of a bellows is avoided, however the arrangement requires a complex seal between conduit and housing.
U.S. Pat. No. 2,751,761 discloses a heat pump with a boiler, in which a single conduit runs helically. The boiler and the conduit respectively form a volume through which a medium flows, the volumes not communicating with each other. Water flows through the boiler, which is optionally heated or cooled by a temperature difference from the medium flowing in the conduit.
From U.S. Pat. No. 4,858,584 there is known a device for preheating of fuel for internal combustion engines. The device comprises a rod-shaped housing and a helical conduit located therein. The housing has at one end an inlet and at the other end an outlet, respectively arranged tangentially.
U.S. Pat. No. 5,379,832 shows a heat exchanger which also has a housing, but in which two conduits are arranged. For the fabrication of the two conduits, a straight pipe is respectively wound around a core, giving the conduits a helical shape. The two conduits may then be interlocked with each other in different ways.